INSECTS. 



plane of position. In some insects they are found inclined or 

 sloped like a roof; in others they are placed horizontally, lying 

 or crossed over one another, or sometimes separated. Some, as 

 the butterflies, raise their wings vertically in repose ; and small 

 hooked setae placed along the side of the upper wings serve to re- 

 tain the lower ones in this position. In the nocturnal Lepidop- 

 tera this is effected by a stiff, scaly, and pointed bristle. Among 

 the insects with four wings the form and relative size of these 

 wings vary much. By their rapid motion they often produce a 

 humming sound ; and among the males of some Orthoptera a 

 stridulous noise, which has been called their song. This sound 

 is produced by the friction of the margins of their elytra upon 

 one another, or by the rubbing of the posterior feet against the 

 wings, and is conceived to be produced for the purpose of cal- 

 ling their females. 



The feet in insects are composed of the hip or coxa, of two 

 joints ; the thigh (femur,) the leg (tibia,) and the toe (tarsus,) 

 divided into many phalanges. The number of joints in the 

 tarsi is constantly five in some orders ; but in others it varies 

 from one to five, and sometimes even the posterior tarsi have 

 a joint less than the anterior ones. Upon the differences in 

 these members the principal divisions of the Coleoptera are es- 

 tablished. The last joint of the tarsi is simple or divided into 

 two lobes, almost always terminated by two claws or hooks, be- 

 tween which in many are remarked from one to three membra- 

 nous cushions or suckers. In the form of the feet, and particu- 

 larly the tarsi, there are certain modifications corresponding to 

 the habits of the insects. The two anterior ones have sometimes 

 the under part of the thighs grooved and armed with small denta- 

 tions ; and their legs or tarsi in this case, terminated by a strong 

 spine, fold with facility on the side of the thighs, and form an 

 organ of prehension. The insects which have the anterior feet 

 disposed in this manner use them for seizing their prey, and are 

 termed raptorii. Others have the tarsi compressed and ciliated 

 or very hairy, demonstrating their aptitude to be used as oars, 

 or for swimming, and these are called natatorii. In the family 

 of bees the legs and the first joint of the tarsi are formed in such 

 a manner as to brush off and carry away the pollen or dust from 

 the stamina of flowers ; and the tarsi and anterior legs in other 

 species are sometimes broad, furnished with dentations or small 



